The adrenal gland is frequently enlarged due to benign non functioning adenomas (85% of incidental adrenal masses) that can be seen on CT. They are also common sites of metastasis of lung cancer. Important neoplasms arising in the adrenal gland are the functioning adenomas (which can cause Cushing's syndrome), adrenocortical carcinoma, and phaeochromocytoma.
Functioning Adenomas
The two common syndromes are Cushing's Syndrome (weight gain, and Primary Hyperaldosteronaemia which leads to hypokalaemia and hypertension. Rarely, sex-hormone tumours may develop. Most cases of non-iatrogenic Cushing's syndrome are due to ACTH producing tumours of the pituitary rather than a primary adrenal adenoma.
Surgical excision is curative.
Differentiation from adrenocortical carcinoma is important as it is a malignant disease. Generally, adenomas have a high lipid content and lower Hounsfeld units ( < 10). Carcinomas are typically denser and have a higher Housfeld units. They may also demonstrate invasion and heterogeneity as well as prolonged contrast uptake.
Adrenocortical Carcinoma
This is a rare tumour of the adrenal gland and is highly malignant.
Diagnosis
Patients may present with virilisation (women), precocious puberty (boys) or with a large abdominal mass (men, non functional tumours).
Staging
The staging system is with TNM and is relatively simple.
T1: < 5 cm
T2: > 5 cm
T3: Extra-adrenal extension
T4: Invasion of adjacent structures or organs
N1: Regional node involvement
M1: Distant metastases
Stage I: T1 N0
Stage II: T2 N0
Stage III: T3 N0 or T1-2 N1
Stage IV: T3 N1 or M1
Management
Surgical excision is necessary for cure and should be undertaken in specialist centres. Tumour spillage is associated with poorer prognosis.
Adjuvant therapy
Adjuvant therapy with mitotane and radiotherapy is commonly used.
Mitotane is a pesticide derivative that acts against the adrenal cortex and malignancies arising from it. It induces adrenal insufficiency and has been shown to be effective for unresectable adrenocortical carcinoma. It use in the adjuvant setting is supported by observational studies that demonstrate improved fewer deaths. Therapy continues for two years after surgery and is usually used for higher risk disease (Ki-67 > 10%, lymphovascular invasion, incomplete resection, tumour spillage).
Radiotherapy is a developing area as previously adrenocortical carcinoma was thought to be radioresistant. In a retrospective review radiotherapy was associated with significantly fewer local recurrences but no effect on overall survival. It is important to include the tumour bed as well as the local lumbar/para-aortic nodes. It is typically recommended for high grade tumours, those with tumour spillage, or those with incomplete resection. Dose should be 50.4 Gy in 28 fractions. Toxicities are standard for upper abdominal radiotherapy and include small bowel obstruction, renal failure, peptic ulcer, and spinal cord injury.
